I am having a problem in displaying anything on the LCD. I spent a lot of time setting the unit up, checking that all the pins and cabling is correct. The LCD has a 14 pin header, with pin #3 supplying the power to change the contrast of the LCD. This voltage is supposed to be adjustable by the small pot on the PLC ( Contrast Adjust ), a voltmeter on pin 3 indicates this pin is very close to ground potential, no matter the pot position, Looking at the PLC Board the pot has three pins, one connected to Pin #3 of the 14 pin header, one to pin #1 of the 14 pin header ( Ground ), the other, should be connected to +5.0 vdc, I could not see where the PCB trace went to, This pin ( on the PC Pot ) has no voltage on it when the unit is powered up. Running the demo programs show the PLC is functioning, but no info is shown on the LCD. Oscilloscope probe shows pulses on all pins but pin 5. So it would indicate that either the contrast is turned off or the new LCD is toast.
The LCD is a brand new Optrex DMC-16230NYJ-LY-CGE-EB unit purchased from Digikey
Any assistance would be appreciated